1. Field
The present invention relates to a magnetic recording medium and a method of manufacturing the same.
2. Description of the Related Art
In order to improve recording density of a magnetic recording medium, a discrete track type magnetic recording medium using discrete tracks is effective in which non-recording regions, where magnetic recording cannot be performed, are formed by removing or modifying the magnetic material between recording tracks on the recording medium and which is capable of suppressing interference in reading from and writing to an adjacent track.
As a method of manufacturing a discrete track medium, there has been known a method of patterning a magnetic material deposited on a substrate for the purpose of forming the magnetic material into such a structure that desired servo signals and recording tracks are isolated. For example, there is known a method in which the magnetic material at the portions corresponding to the non-recording regions is removed, and then recesses where the magnetic material has been removed are filled with a filling material to flatten the surface of the medium. Alternatively, there is known another method in which the magnetic material at the portions corresponding to the non-recording regions is chemically modified to locally deactivate the magnetic material, thereby patterning the magnetic material (for example, Jpn. Pat. Appln. KOKOKU Publication No. 5-47918).
In the discrete track type magnetic recording media provided by using the above methods, since the magnetic material is locally modified or the recesses between the magnetic material are filled with a different material, interfaces are produced between the magnetic material constituting recording regions and the non-recording regions in the medium. The interfaces are continuously formed to the surface of the magnetic recording layer and usually separated from the air only by a protective film.
However, voids may be produced at the interfaces between different materials due to difference in thermal expansion coefficients and difference in surface energy, represented by hydrophilic and hydrophobic properties, of the two materials. The voids produced in the medium often become a cause of so-called corrosion. Specifically, when the protective film has an incomplete structure, mainly water in the air enters the medium through the protective layer and along the interfaces to induce the corrosion. When the corrosion occurs, chemicals may be precipitated on the medium surface.